Patterned tubing

ABSTRACT

A welded, hollow metal tubing having formed patterns in or upon the tubing wall where the formed pattern is interrupted by contiguous wall sections or segments which are free of said formed pattern facilitating the manufacture of discrete tube lengths having smooth or patterned wall structure in any desired continuity or configuration.

United States Patent 1191 1111 3,902,552 McLain Sept. 2, 1975 PATTERNED TUBING 2,463,997 3/1949 Rodgers 165/179 2,864,591 12/1958 Frink [751 Charles Alto", 3,154,141 10/1954 Huet 165/185 [73] Assgneez ggg New Haven FOREIGN PATENTS 01R APPLICATIONS l d S 6 l 4 221,024 12/1908 Germany 138/38 [22] Fi e ept. 97

[21] Appl. No: 506,457 Primary Examiner-Charles J. Myhre Assistant ExaminerT. W. Streule, Jr. Relaed Apphcatlon Data Attorney, Agent, or FirmJoseph Fleischer; Robert H. [63] Continuation-impart of Ser. No. 359,019, May 10, Bachman 1973, abandoned, which is a continuation-in-part of Ser. Nos. 214,034, Dec. 30, 1971, abandoned, and Ser. No. 218,422, Jan. 17, 1972, abandoned. [57] ABSTRACT A welded, hollow metal tubing having formed patterns S 165/179 I l i ig in or upon the tubing wall where the formed pattern is Fieid 5' 138/38 interrupted by contiguous wall sections or segments H71 1 6 72/366 which are free of said formed pattern facilitating the manufacture of discrete tube lengths having smooth or References Cited patterned wall structure in any desired continuity or configuration.

8 Claims, 12 Drawing Figures PATENTED 1 75 saw 3 o g TUBE FORMING M/L L PATENTEDSEP 2mm l/VELD BEAD REMOVAL WELDING 5T4 T/ON SI-IA PING AND OR SIZING SHEET u. o g

TUBE

FORMING STRIP CORRUGA TING SE PA RA TING STA T ION STRIP SUPPLY CUT cur

PATTERNED TUBING CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuatiomin-part of copend' ing application Ser. No. 359,019, filed May 10, 1973, by Charles D. McLain, which in turn is a continuationin-part of applications Ser. No. 214,034, filed Dec. 30, 1971 now abandoned, and Ser. No. 2 l 8,422, filed Jan. 17, 1972, by Charles D. McLain now abandoned.

BACKGROUND OF THE INVENTION This invention relates to the continuous fabrication of tubing using metallic Strip as a starting material.

For example, metallic strip of predetermined width and indefinite length having side edges is advanced continuously through a tube forming mill to curl the strip into a tube with the side edges abutting one another to form a longitudinal seam. The seam is continu ously closed by welding or other suitable operation to produce a fluidtight endless tube.

The cited applications Ser. Nos. 214,034 and 218,422 are directed to tube forming processes which include continuously embossing one or more surfaces of the strip in accordance with any desired pattern prior to entry into the tube mill so that the tubing ultimately formed has an embossed surface on the interior or the exterior or both surfaces of the tube wall as desired. Obviously, the pattern structure is a matter of choice consistent with the ultimate use of the tubing.

The cited applications Ser. Nos. 214,034 and 218,422 are also directed to physically and continuously deforming the strip, prior to entry into the tube mill, by generating longitudinal, spiral or transverse striations, grooves or channels in the strip. Thus, the tube ultimately fabricated from deformed strip has a wall structure which has been physically shaped in one fashion or another in contrast to tube wall structure developed from embossed strip. Here again, the pattern generated by deforming the strip is a matter of choice governed by ultimate tube use.

Accordingly, said applications Ser. Nos. 214,034 and 218.422 deal with tubing made from strip formed with a pattern by embossing, etching or similar surface treatmentor with tubing made from strip formed with a pattern by corrugating, crimping or other metal forming process. These applications also disclose that in the case of strip surface treatment a pattern may be generated on one or more sides of the strip so that the wall of the tube ultimately formed may carry a pattern on the internal wall surface or the external wall surface or on both wall surfaces. as desired. Obviously, if the pattern is generated by deforming the strip, it will appear on the interior as well as the exterior of the tube wall.

For purposes of disclosing and claiming the present invention surface treatments on one or more sides of the strip or deformation of the strip, which generate discernable surface indicia or which generate deformed wall structure in the tubing, are all referred to as "formed pattern". pattern forming, orfpattern.

The method of developing the pattern by surface treatment or the method of developing the pattern by deforming the strip are a matter of choice and are not critical to the principles of the present invention.

Therefore, it is to be understood that the language pattern. formed pattern, or pattern forming as applied to the metallic strip is intended to include any process or operation which removes metal from any surface of the strip or which physically deforms the strip prior to entry into the tube mill.

Obviously, the term pattern is intended to define the result of such metal removal or metal deformation.

SUMMARY OF THE INVENTION It is a principal object of the present invention to provide discrete lengths of tubing having wall segments or sections defining formed patterns interrupted by contiguous wall segments which are smooth or free of said formed pattern.

It is an additional object of the present invention to continuously fabricate tubing from metallic strip where discrete lengths of tubing are formed with discontinuous patterns in various combinations and permutations and the discontinuities are exemplified by intervening and contiguous tube segments which are smooth or free of a pattern.

It is a further object of the invention to provide an improved procedure for generating tubing from metallic strip where the tubing fabricated has a wall formed with a pattern interrupted by contiguous wall segments which are smooth or free of a formed pattern, giving one the option to separate the tubing into discrete lengths in the region of a pattern or in the region of a smooth segment.

A process embracing certain principles of the present invention may comprise the steps of: providing a strip of metal of predetermined width, indefinite lengths and side edges; continuously advancing the strip; continuously forming patterns on at least one surface of the strip during the course of advance; intermittently interrupting the pattern forming step to break the continuity of the formed pattern and to create intervening smooth segments in said surface defining a discontinuous pattern; continuously forming said strip into a tube by abutting the side edges to create a longitudinal, axially extending, continuous seam; continuously welding said seam to create a fluid-tight seal; and thereafter continuously separating the tubing into discrete lengths, said separating step occurring in the regions of the tube defined by said smooth segments.

Accordingly, the tubing of the present invention comprises: a welded, hollow metal heat exchanger tubing formed from metal strip material and having a 10ngitudinally extending weld seam, said tubing having a given wall thickness and an inside surface corresponding to one side of said strip material and an outside surface corresponding to the opposing side of said strip material, a heat exchange enhancement pattern embossed into at least one of said surfaces by embossing the corresponding side of said strip, the continuity of the formed pattern being interrupted to create inter vening smooth segments in said surface and a discontinuity in the pattern, whereby said tubing may be separated into discrete lengths of tube having alternating smooth segments and patterned segments.

Other features and advantages of the present invention will become more apparent from an examination of the succeeding specification when read in conjunction with the appended drawings, in which:

BRIEF DESCRIPTION 'OF DRAWINGS FIGS. 1, 2 and 3 are representative examples of discrete lengths of tubing illustrating contiguous smooth and patterned wall segments or sections;

FIGS. 4 and 5 show typical mill rolls for generating patterns on the strip surface;

FIG. 6 shows a typical pair of mill rolls operative to generate a pattern by deforming the strip;

FIG. 7 shows a finished segment of tubing where the pattern is interrupted by a smooth Wall;

FIG. 8 shows a typical tube forming die;

FIG. 9 is a side view of a mill arrangement operative to generate patterns on the strip in discontinuous fashion;

FIG. 10 shows, schematically, a typical tube forming operation starting with the strip supply and ending with tube cutting or separation;

FIGS. 11 and 12 illustrate points at which the tube may be separated or cut into discrete lengths.

Referring now to FIGS. 1, 2 and 3, the reference numeral 10 designates a finished length of tubing having smooth ends 11 and 12 intermediate patterned segment 13. In this case, the internal surface of the tube 14 is smooth throughout.

FIG. 2 shows a length of tubing 15 having a smooth external surface 16 throughout its length with an interior patterned surface 17 terminating in smooth ends 18 and 19.

FIG. 3 shows a still further variation in that tube 20 formed with a diamond knurled pattern 21 throughout its interior and the exterior surface is smooth as at 22 and patterned at each end as indicated by the reference numerals 23 and 24.

FIGS. 4 and 5 each illustrate a pair of cooperating mill rolls, 26-27 and 28-29 operative to form a pattern P on one or both surfaces of strip S as disclosed in said previously noted applications.

FIG. 6 shows mill rolls 31-32 operative to physically deform strip S by generating longitudinally extending striations or corrugations indicated by the reference numeral 33, also disclosed and described in the previously noted applications.

In FIG. 7, a discrete length of tubing 34 is formed with a pattern 3636 interrupted by contiguous smooth segment 37.

In FIG. 8, the strip of FIG. 6, is shown in the course of tube forming wherein end edges 38 and 39 abut one another to generate a longitudinal seam 41 as disclosed and described in said previously noted applications.

Referring now to FIG. 9, the reference letter M designates a pattern forming mill comprising a series of pattern forming rolls 42-43, 44-46 and 47-48 which are operable in timed sequence (in accordance with the length of pattern that one desires to generate) to move from an operative position indicated by the reference numeral 49 to an inoperative position indicated by the reference numeral 51. By appropriate control or programming of the operative and inoperative condition of the various pairs of mill rolls, one can generate a broken or interrupted pattern on the strip in accordance with various combinations or permutations, as desired.

For example, a discontinuity of pattern can be generated on the bottom surface 52 of the strip leaving the top surface 53 smooth, or vice versa.

Obviously, if one surface or the other is intended to be smooth throughout, a smooth roll must be placed in working contact with that surface.

Furthermore, with appropriate programming, the pattern forming mill M can be operated to generate pattern discontinuities in top and bottom surfaces of the strip (interior and exterior surfaces of tubing) which are phased (or displaced) from one another so that a particular tube segment ultimately formed can be smooth (or formed with a pattern) on both surfaces in a particular selected segment or a pattern can be displaced on one surface relative to the pattern on the opposite surface. Thus, smooth and patterned tube segments on the interior and exterior surfaces of a given length of tubing can be phased or displaced as design considerations in the ultimate use of the tube dictate.

For example, FIG. 3 shows a displaced pattern in that segment 22 on the exterior surface of the tube 20 is smooth, while the interior surface 21 is formed with a pattern throughout without any discontinuity. A similar structure is shown by window 50 in FIG. 11. Naturally, if desired, a phased pattern may be used on the inside as well as on the outside of the tube.

Frequently, it is necessary to size the strip before its entry into the tubes to insure a neat, uniform longitudinal seam. Typically this involves scarfing, bevelling or shearing the side edges of the strip starting material to create a uniform cross-sectional configuration in the strip before entry into the tubes.

It is to be understood that the process steps of the present invention can be practiced on virtually any metallic strip which is susceptible of pattern forming.

Furthermore, while one principal use of tubing fabricated in accordance with the principles of the invention involves heat exchanger applications, it is entirely within the scope of the invention to utilize the exterior ornamentation and aesthetic design features of the finished tubing in applications other than in the field of heat exchangers.

It is anticipated that a variety of pattern modifications may be devised as considerations of thermal engineering, construction and ornamentation may dictate without departing from the spirit and scope of the invention.

What is claimed is:

1. A welded, hollow metal heat exchanger tubing formed from metal strip material and having a longitudinally extending weld seam, said tubing having a given wall thickness and an inside surface corresponding to one side of said strip material and an outside surface corresponding to the opposing side of said strip material, a heat exchange enhancement pattern extending throughout only a portion of the tube wall thickness embossed into at least one of said surfaces by embossing the corresponding side of said strip, the continuity of the formed pattern being interrupted to create intervening smooth unembossed segments in said surface and a discontinuity in the pattern, whereby said tubing may be separated into discrete lengths of the tube having alternating smooth segments and patterned segments.

2. A tubing according to claim 1 whereby said tubing may be separated in the regions defined by said pattern into discrete lengths of tube having patterned ends and an intermediate smooth segment.

3. A tubing according to claim 1 whereby said tubing may be separated in the regions defined by the smooth segments into discrete lengths of tube having smooth ends and an intermediate patterned segment.

4. A tubing according to claim 1 wherein both of said surfaces have a heat exchange enhancement pattern.

5. A tubing according to claim 4 wherein the pattern on the inside surface of said tubing differs from the pattern on the outside of said tubing.

nuity in both the pattern on the inside surface and the pattern on the outside surface, wherein the pattern discontinuity on the outside surface is in phase with the corresponding discontinuity on the inside surface.

l =l i 

1. A welded, hollow metal heat exchanger tubing formed from metal strip material and having a longitudinally extending weld seam, said tubing having a given wall thickness and an inside surface corresponding to one side of said strip material and an outside surface corresponding to the opposing side of said strip material, a heat exchange enhancement pattern extending throughout only a portion of the tube wall thickness embossed into at least one of said surfaces by embossing the corresponding side of said strip, the continuity of the formed pattern being interrupted to create intervening smooth unembossed segments in said surface and a discontinuity in the pattern, whereby said tubing may be separated into discrete lengths of the tube having alternating smooth segments and patterned segments.
 2. A tubing according to claim 1 whereby said tubing may be separated in the regions defined by said pattern into discrete lengths of tube having patterned ends and an intermediate smooth segment.
 3. A tubing according to claim 1 whereby said tubing may be separated in the regions defined by the smooth segments into discrete lengths of tube having smooth ends and an intermediate patterned segment.
 4. A tubing according to claim 1 wherein both of said surfaces have a heat exchange enhancement pattern.
 5. A tubing according to claim 4 wherein the pattern on the inside surface of said tubing differs from the pattern on the outside of said tubing.
 6. A tubing according to claim 1 including a longitudinally extending corrugated pattern.
 7. A tubing according to claim 1 including a diamond knurled pattern.
 8. A tubing according to claim 3 including a discontinuity in both the pattern on the inside surface and the pattern on the outside surface, wherein the pattern discontinuity on the outside surface is in phase with the corresponding discontinuity on the inside surface. 